The goal of this project is to evaluate the toxicity C9-alkylbenzenes, including 1,2,4-trimethylbenzene and a 2-ethyltoluene, following exposure via inhalation. Three-month studies of 1,2,4-trimethylbenzene are in the pathology/reporting phase. 2-week studies of 2-ethyltoluene are approved and will be used to design 3-month studies. Humans are likely to be similarly exposed to these compounds via inhalation. These subchronic studies will provide valuable data on general toxicity as well as reproductive and neurotoxicity and will aid in the design of chronic toxicity/carcinogenicity studies. Keywords: toxicity, inhalation, vanadium, trimethylbenzene, ethyltoluene.